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MOJ Sports Medicine

Mini Review Open Access Therapeutic : myths and truths for non- portable in-clinic and portable home use ultrasound

Therapeutic ultrasound was first discovered prior to World War II Volume 4 Issue 4 - 2020 when German scientists were experimenting with sonar in submarines 1 2 and found an interesting biophysical effect. When sound was released David Draper, Rajiv M Mallipudi 1 from the vessel to detect objects in the surrounding water, the Professor, Exercise Sciences, Brigham Young University, USA 2Unit Medical Director, Yale New Haven Health, Clinical scientists noted that fish absorbed sound waves and died. Thus, the Instructor, Yale School of Medicine, USA idea of ultrasound producing biological effects was born.1 Correspondence: David Draper, Professor, Exercise Sciences, Therapeutic ultrasound is one of the most commonly used Brigham Young University, USA, Email modalities that clinicians employ to treat orthopedic and muscle injuries, and often used for pain relief.2-4 With appropriate use by a Received: October 01, 2020 | Published: November 02, 2020 competent therapist, ultrasound can provide several benefits for treating strains, , tissue healing and pain.5-9 However, therapeutic ultrasound is one of the most misunderstood and, therefore, one of the most misused and underused modalities. heat to the target area. Based upon this, (SPI and SATP) should be Unfortunately, the majority of the time that ultrasound is used, it included when reporting the parameters of therapeutic ultrasound.11 is used by someone with little knowledge of the device or its use. Myth 3. Patients do not feel anything during an ultrasound At times, some healthcare professionals rarely read the literature treatment. concerning ultrasound. Instead they depend on being trained by their co-workers. If wrong parameters and inadequate dosimetry are used Truth 3. The only reason a patient may not feel therapeutic on the patient, there may be negligible or even adverse outcomes.1 ultrasound in a device is when the power output is too low (low duty cycle or low intensity). For example, a treatment at a duty cycle The purpose of this article is two-fold. First, it aims to compare of 25%, and an intensity of 0.5W/cm2, is too low to bring about a traditional ultrasound with wearable ultrasound. Second, this review therapeutic benefit.11 provides corrections for mistakes clinicians often make when applying (and prescribing) ultrasound for treatment. Myth 4. Increasing the ultrasound intensity (W/cm2) increases the depth of tissue penetration. Myth 1. Warm whirlpools, paraffin baths, and silicate-gel heating packs all produce therapeutic heat. Thus, there is no reason to Truth 4. Both the intensity and of the ultrasound employ ultrasound. determines the depth of penetration into the tissue for therapeutic treatment. Turning up the intensity will send a stronger ultrasonic Truth 1. While these 3 modalities produce therapeutic heat, signal into the tissue which will propagate deeper.12 The absorption their depth of penetration is shallow.10 Several years ago, scientists rate of ultrasound is also proportional to frequency. The higher the compared ultrasound heat with whirlpools, paraffin bath and hot packs frequency, the more quickly energy is absorbed. For example, with the at 1cm depth in human triceps surae muscle. These 3 devices only ultrasonic intensity being held equivalent, 1MHz ultrasound would raised the temperature 2°C at this therapeutic depth. At a greater depth show a similar energy signature in tissue from 2.5-5cm deep, as 3MHz (3cm), there was no temperature change for non-ultrasound-based ultrasound would from the surface to 3cm deep.13 techniques. At 1cm depth ultrasound raised the muscle temperature 6°C. At 3cm the muscle temperature was raised over 4°C. Therefore, Myth 5. Applying an ice pack prior to an ultrasound treatment when deep heat is desired, ultrasound is the modality of choice.1 increases tissue heating. ­Ultrasound generates deep heat by the absorption and conversion of ultrasound into thermal energy (rapid vibration of molecules) within Truth 5. According to this theory, applying a cold pack to the the tissue matrix. tissues initiates physiological responses such as vasoconstriction and decreased blood flow. Thus, cooling the area not only results Myth 2. Pulsed ultrasound does not heat tissues. in decreased local temperature, but it may temporarily increase the density of the tissue being treated. This occurs by decreasing Truth 2. Research performed by Gallo11 shed light on the fact that superficial attenuation and facilitating ultrasound transmission to pulsed ultrasound can heat treated tissues. Spatial Peak Intensity (SPI) deeper tissues, thus enhancing the thermal effects of ultrasound. This is the maximum output over time. Spatial Average Temporal Peak theory has been refuted several times. In 2 studies, an ice pack was (SATP) is the result of only pulsed ultrasound. The SATP during the applied to human tissue for 5 minutes prior to ultrasound. The ice ON time of a pulse is displayed as intensity on the machine’s output dropped the temperature so much that the ultrasound treatment could meter. Gallo compared muscle temperature increase during ultrasound not raise the tissue temperature to even 50% of those who received application. In group 1, pulsed ultrasound at a 50% duty cycle was identical ultrasound with no prior ice treatment.14,15 Ultimately, it does applied for 10 minutes at 1W/cm2 over a 2 ERA (effective radiating not make sense to cool something that you immediately want to heat, era). The second group received 10 minutes of continuous ultrasound particularly if you have limited time with the patient and cannot allow at 0.5W/cm2. The results showed that both treatments applied modest the tissue to equilibrate.

Submit Manuscript | http://medcraveonline.com MOJ Sports Med. 2020;4(4):115‒116. 115 ©2020 Draper et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Copyright: Therapeutic ultrasound: myths and truths for non-portable in-clinic and portable home use ultrasound ©2020 Draper et al. 116

Myth 6. , , and muscle tissue heat at the same commonly used in-clinic use of therapeutic ultrasound versus newer rate during thermal ultrasound treatments. wearable sam® technology. With appropriate parameters, one can find ways to use both in-clinic and wearable ultrasound to effectively Truth 6. Tendons heat up 3 times faster than muscle tissue when treat injuries.18,19 3MHz ultrasound is used.16,17 Why does this happen? Muscle tissue has more blood flow than tendons. Thus, the increased blood flow References serves to prevent excessive heating since it can pull the heat away from the area of injury. However, since tendons have little blood flow, 1. Draper DO, Jutte SL, Knight KL. Therapeutic Ultrasound: The Art and they heat up quicker. It is important to keep in mind that the dose Science. 2020. Wolters Kluwer, Baltimore. and duration must be adjusted to prevent overheating of the tendons 2. Kuitert JH. Ultrasonic energy as an adjunct in the management of during the ultrasound treatment. radiculitis and similar referred pain. Am J Phys Med. 1954;33(1):61–65. Non-portable in-clinic ultrasound is one of the most frequently 3. Nwuga VCB. Ultrasound in treatment of back pain resulting from applied therapeutic modalities in the world. It can be a very effective prolapsed intervertebral disc. Arch Phys Med Rehabil. 1983;64(2):88–89. treatment, but does require patient access to the healthcare provider 4. Soren A. Evaluation of ultrasound treatment in musculoskeletal disorders. multiple times per week which can prove challenging to some patients Physiotherapy. 1995;81:214–217. – especially during the COVID-19 pandemic! In the past decade, a 5. Aides JH, Jadeson WJ. Ultrasonic energy in the treatment of hypertrophic small, wearable ultrasound device has been developed for home use. in elderly patients. Ann W Med Surg. 1952;6(9):545–550. The sam® (Sustained Acoustic Medicine) device is wearable and self- administered that provides up to 4 hours of treatment a day to treat 6. DePreux T. Ultrasonic wave therapy in osteoarthritis of the hip joint. B J injuries. Phys Med. 1952;5:14–1.9 7. Markham DE, Wood MR. Ultrasound for Dupuytren’s contracture. SAM Traditional ultrasound Physiotherapy. 1980;66(2):55–58. Treatment duration 8. Gorkiewicz R. Ultrasound for subacromial . Phys Ther. 1984:64:46–47. Up to 4 hrs. 5-15 mins 9. Binder A. Is therapeutic ultrasound effective in treating lesions? Frequency Br Med J(Clin ResEd). 1985;290:512–514. 3MHz 1.5MHz 10. Dyson M. Mechanisms involved in therapeutic ultrasound. Physiotherapy. Indications 1987; 73:1160–1120. Soft tissue injuries, pain Same 11. Gallo JA, Draper DO, Thein–Body L, et al. A comparison of human muscle temperature increases during 3MHz continuous and pulsed ultrasound Effective daily dose with equivalent temporal average intensities. JOSPT. 204;34:395–401. 18,720 Joules ~ 2,000-5000 Joules 12. Ter Harr G. Basic physics of therapeutic ultrasound. Physiotherapy. 1978;64(4):110–113. Heating 13. Draper DO, Castel JC, Castel D. Rate of temperature increase in human About half as much as traditional ultrasound muscle during 1MHz and 3MHz ultrasound. J Orthop Sports Phys Ther. Intensity 1995; 22(4):142–150. 14. Draper DO, Schulties S, Sorvisto P, et al. Temperature changes in deep 0.132 W/cm2 0-5W/cm2 muscles of humans during ice and ultrasound therapies: an in–vivo study. Size of crystals JOSPT. 1995;21(3):153–157. 2 at 6cm2 2.5cm2 15. Rimington SJ, Draper DO, Durrant E, et al. Temperature changes during therapeutic ultrasound in the pre–cooled in the human gastrocnemius Portable muscle. J Athl Train. 1994;29(4):325–327. Yes No 16. Chan AK, Myrer JW, Measom G, et al. Temperature changes in human patellar in response to therapeutic ultrasound. J Athl Train. The benefits of SAM over other non-portable ultrasound devices 1998;33(2):130–135. is that it is capable of delivering daily ultrasound at home or in the office for up to 4 hours at a time. A joule is the amount of energy 17. Draper DO, Edvalson CG, Knight KL, et al. Temperature increase in the human Achilles tendon during ultrasound treatments comparing per treatment. Traditional ultrasound is applied for 5-15 mins. If commercially made ultrasound gel, full–thickness and half–thickness gel the intensity is high, between 2,000-5,000 Joules may be produced. pad mediums. J Athl Train. 2010;45(4):333–337. However, the 4 hour sam® treatment can produce nearly 4 times as much (18,000 joules) as traditional ultrasound. The portable sam® 18. Draper DO. Ten mistakes commonly made with ultrasound use: current device can be used at home at any time of the day and during any research sheds light on myths. Athletic Training: Sports Health Care Perspectives. 1996;2:95–107. activity; however, traditional ultrasound requires application by a therapist in the clinical facility. 19. Draper DO. Facts and misfits in ultrasound therapy: steps to improve your treatment outcomes. Eur J Phys Rehabil Med. 2014;50(2):209–216. This review helped clarify several misconceptions about the administration of ultrasound. In addition, it provided a comparison of

Citation: Draper D, Mallipudi RM. Therapeutic ultrasound: myths and truths for non-portable in-clinic and portable home use ultrasound. MOJ Sports Med. 2020;4(4):115‒116. DOI: 10.15406/mojsm.2020.04.00107